Survival in small cell lung carcinoma is independent of Bcl-2 expression.

Bcl-2 overexpression is a common event in small cell carcinomas (SCLC). The bcl-2 oncoprotein has a unique oncogenic role by inhibiting programmed cell death (apoptosis), resulting in tumorigenesis and chemoresistance. Forty-two cases of SCLC were stained immunohistochemically with bcl-2 monoclonal antibody (Biogenex, San Ramon, CA) after using an antigen retrieval step with citrate buffer. bcl-2 positivity was determined as detection of the oncoprotein in greater than 10% of noncrushed neoplastic cells. Twenty-five of 42 (60%) patients had extensive disease at presentation, 10 of 42 (24%) had limited disease, and 7 of 42 (16%) had disease localized to the lung. Twenty-four of 42 (57%) tumors were bcl-2 positive, and 18 of 42 (43%) tumors were bcl-2 negative. Follow-up in patients ranged from 7 days to 96 months (mean follow-up, 20 months). The median survival of patients with bcl-2-positive tumors was 11 months, as opposed to 13 months for bcl-2-negative tumors. There was no significant difference in median survival between bcl-2-positive and bcl-2-negative SCLC (log rank test, P = .2256). Using Cox's proportional hazards model, median survival in SCLC was determined to be independent of age at diagnosis, stage at presentation, therapeutic modality, and bcl-2 expression. bcl-2 expression does not significantly influence survival in SCLC.